Push-to-expand mandrel for stretch-wrap hand tool

ABSTRACT

The present disclosure relates to a dispenser for use with rolls of film material, particularly coreless rolls. The mandrels of the dispenser can move between a retracted position wherein the dispenser has a reduced diameter, such as for when the dispenser is being inserted into a roll of film, and an increased diameter, such as for when the film is being dispensed from the dispenser. The mandrels have sections which are joined by various spring configurations and are formed as being axially slidable with respect to a central shaft with lug elements. As the mandrel is slid along the central shaft, the lug elements deflect the spring configurations outwardly so as move the mandrels radially outwardly and increase the radius of the dispenser.

This application claims priority under 35 U.S.C. §119(e) of provisional application Ser. No. 61/131,691 filed on Jun. 11, 2008, the contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dispenser with a mandrel which can be radially expanded by a longitudinal pushing action in order to engage a roll of material, particularly stretch wrap material, more tightly.

2. Description of the Prior Art

In the prior art, there are many types of dispensers for an operator to hold a film roll and to apply tension on the film while hand wrapping a typical pallet load. Most of the commercial film rolls use paper cores on the internal diameter of the film roll, which helps to reinforce the roll from bending and to protect the film particularly toward the end of the roll. There are many different commercial types of dispenser mandrels and end cups used with the paper core rolls. Typically these types of mandrels are pressed through and/or slipped across the length of the inner diameter of the paper core. The prior art likewise includes a device which has fingers on the mandrel that deflect radially, while being pushed into the roll, to grip the paper roll and compensate for minor variations in the inner diameter.

There are also low cost end-cups or end-handles used to support the paper core film rolls as an alternative to the operator using their fingers or hands to hold the film roll during the wrapping of the pallet.

With respect to coreless film rolls (i.e., those rolls that do not have a paper core on the inner diameter of the roll), the assignee of the present application provides a device with fingers on the mandrel which deflect radially, after entering the roll, to compensate for variation in the inner diameter of the film rolls.

Moreover, many of the standard commercial dispensers that use mandrels and end-cups or end-handles would not be acceptable for use in a coreless film roll. The film layers toward the end of the roll or closest to the inner diameter of the film roll would be damaged by the friction and pressure that occurs when the mandrel is pressed through the core of the roll during loading. Additionally, the edges of the film roll near the internal diameter of the core can be damaged by the end-cups and end-handles, which typically have ends which are tapered inwardly and can dig into the film layers.

The device of the assignee of the present application, as described above, includes a mandrel that compensates for some radial distortion in the three inch inner diameter coreless film roll, but the three longitudinal gripper bars do not flex enough to cover the range of tolerance on the new two inch coreless film rolls. Additionally, like other commercial dispensers, the gripper bars or end cups can overstress the film layers during loading.

When the film layers at the end of the roll are damaged, particularly on the edges, typically the film will “barber-pole” or tear off at an angle. This results in waste of many feet of stretch film and further result in great difficult in removing the wasted film from the mandrel. Further refinements to this device have been sought, but have not been found to be satisfactory.

Another commercial dispenser has flanged slip rings that have tabs that are cut out of the flange on three sides with the bend line across the flange. When the operator engages the tabs with his thumbs, the tabs engage protrusions on the cups of the mandrel that hold the film roll. The tabs act as a brake that transmits the force from the operator's wrist into torque on the film roll. The engaging of the tabs is difficult to control and can transmit a jerking force on the film roll, which can cause the film to snap or break.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a dispenser for film handling which reduces damage to film and which allows the coreless film roll to be fully unwound with reduced or eliminated waste of film.

It is therefore a further object of the present invention to provide a dispenser which can be easily inserted into a coreless roll with reduced or eliminated snagging and damaging of the film.

These and other objects are attained by providing a dispenser with a mandrel which expands radially in response to axial motion of an internal shaft, which includes cam elements, thereby moving the mandrel sections radially outward. The mandrel sections which expand radially outward against the internal diameter of a core or coreless film roll in response to the axial motion of an internal shaft can be implemented by at least two embodiments. The first embodiment uses a mandrel with a leaf-spring configuration in which the sections themselves expand uniformly outward. The second embodiment uses a mandrel with a collet-spring configuration. In either case, the mandrels are unlikely to damage the layer of film nearest the inside of the film roll at the edges.

Moreover, the mandrels can contract so that the mandrel can be removed from a coreless roll with a greatly reduced likelihood of damage. The shaft extension or retraction causes the mandrels of the dispenser to expand or contract uniformly and is a motion that typically does not interfere with the typical rotary motion of the dispenser during unwinding.

DESCRIPTION OF THE DRAWINGS

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

FIG. 1A is a perspective view of a first embodiment of the dispenser of the present invention, shown in a radially expanded configuration.

FIG. 1B is a perspective view of a first embodiment of the dispenser of the present invention, shown in a radially contracted configuration.

FIG. 2 is a perspective view of a first embodiment of the dispenser of the present invention, shown with one cup exploded from the dispenser.

FIG. 3 is a perspective exploded view of the first embodiment of the dispenser of the present invention.

FIG. 4 is a cross-sectional view along FIG. 1A.

FIG. 5 is a perspective exploded view, showing the structure of the shaft and the leaf-spring configuration of the mandrel of an embodiment of the dispenser of the present invention.

FIG. 6 is a perspective view of a second embodiment of the dispenser of the present invention, using a collet spring configuration.

FIG. 7 is an exploded view of a second embodiment of the dispenser of the present invention, using a collet spring configuration.

FIG. 8 is a perspective view of the second embodiment of the dispenser of the present invention, along with a roll of film material.

FIG. 9 is a perspective view of an embodiment of the dispenser of the present invention inserted into a roll of film material.

FIG. 10 is a perspective, partially exploded, view of the second embodiment of the present invention, shown with a bottom fitment in a handle shape.

FIG. 11 is a perspective view of the embodiment of the dispenser of FIG. 10, shown with a roll of film material.

FIG. 12 is a perspective view of a cup which can be used with embodiments of the present invention, shown with a slip ring.

FIG. 13 is an exploded perspective view of the cup of FIG. 12, shown with a slip ring.

FIG. 14 is a perspective cut-away view of the cup of FIG. 13.

FIG. 15 is a perspective view of a slip-ring sleeve.

FIG. 16 is a second perspective view of a slip-ring sleeve.

FIG. 17 is a perspective view of a variation of the first embodiment of the dispenser of the present invention illustrated in FIGS. 1 and 2, shown with a straight handle bar in lieu of a top cup.

FIG. 18 is a perspective view of the straight handle bar of FIG. 17.

FIG. 19 is a perspective cut-away view of the straight handle bar of FIG. 18.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings in detail wherein like numerals indicate like elements throughout the several views, one sees that FIGS. 1A, 1B, 2, 3 and 4 are various views of a first embodiment of dispenser 10. Dispenser 10 includes a central shaft 12, with a square or rectangular cross section, with cam lugs 14 protruding from two opposing sides of central shaft 12. Cam lugs 14 can be integrally molded with central shaft or can be attached thereto. The cam lugs 14 include expanded or bulbous heads 15 which serve to slidingly engage the mandrels thereto. Central shaft 12 includes first end 16 and second end 18. First end 16 of shaft 12 includes a portion 32 of circular cross section and further includes longitudinal blind aperture 34 which receives longitudinal male portion or stem 36 of first cup 38 thereby holding cup 38 so that first cup 38 moves in concert with central shaft 12. First cup 38 can be replaced with an axially oriented handle 39 as illustrated in FIG. 17. Second end 18 includes a section 20 with a round cross section of reduced cross sectional dimensions with respect to the remainder of central shaft 12. Section 20 further included enlarged head 21.

Mandrels 40, 42 are positioned in axial sliding engagement about the exterior of central shaft 12 and held in sliding engagement with the central shaft 12 by bulbous heads 15 of cam lugs 14. The square or rectangular cross section of central shaft 12 allows the mandrels 40, 42 to guide and slide against the parallel faces on each side of the central shaft 12. As best shown in FIG. 3, mandrel 40 includes opposed mandrel sections 44, 46 extending from and integrally formed with first half 25 of second cup 29 while mandrel 42 includes opposed mandrel sections 48, 50 extending from and integrally formed with second half 27 of second cup 29. Axial passageway 24 is formed inwardly adjacent from first and second halves 25, 27 of second cup 29. When mandrels 40, 42 are attached together, typically by screws (see, for instance, screw apertures 31 outward of axial passageway 24 in FIG. 3), section 20 of second end 18 is captured within axial passageway 24 with relative axial sliding of section 20 permitted within axial passageway, limited by expanded head 21. With this configuration, mandrels 40, 42 are integral with, and therefore move in concert with second cup 29 while central shaft 12 moves in concert with first cup 38.

Opposed mandrel sections 44, 46, as well as opposed mandrel sections 48, 50, while integrally formed with each other, are held in position with respect to each other by various configurations of spring and cam configurations. Typically, the springs are configured in tension so as to urge together the opposed mandrel sections 44, 46, as well as mandrel sections 48, 50. Likewise, the cam configuration, in response to the movement of the mandrel sections against cam lugs 14, forces apart the mandrel sections 44, 46 as well as the mandrel sections 48, 50 when the mandrels 40, 42 are urged axially along the central shaft 12, typically by manual urging of the second cup 29 (which moves in concert with the mandrels 40, 42) or the first cup 38 (which moves in concert with the central shaft 12). The resulting radial movement of the mandrel sections 44, 46, 48, 50 results in an increased radius of the dispenser 10.

It is generally envisioned that the cam action is configured so that the movement of the mandrels would cause urging of at least a portion of the springs against the cam lugs 14 so as to change the configuration of the spring, either urging apart or urging together the mandrel sections 44, 46 as well as the mandrel sections 48, 50.

Conversely, it is envisioned that the springs could be configured in compression so as to urge apart mandrel sections 44, 46 as well as mandrel sections 48, 50, and that the action of the cam configuration, in response to the movement of the mandrel sections against cam lugs 14, would urge apart mandrel sections 44, 46 as well as mandrel sections 48, 50.

More specifically, in the first embodiment, as shown in FIGS. 1A, 1B, 2, 3 and 4, mandrel sections 44, 46 as well as mandrel sections 48, 50 are held together by a cantilever spring configuration (which may be integrally molded or otherwise attached to the mandrel sections) which has an alternating sequence of extension leaf springs 60 and contraction leaf springs 62. Extension leaf springs 60 include upper and lower prongs 61, 63 whose distal ends touch each other in the configuration of FIG. 1B and are separable from each other. Extension leaf springs 60 provide the cam configuration by moving outwardly when deflected by cam lugs 14 whereby that the upper and lower prongs 61, 63 separate from each other, but also have some over-travel capacity to compensate for the variation in the internal diameter of the roll 100. The extension leaf springs 60, typically made of plastic, can be reinforced with elastic O-rings or the equivalent to counter cold creep and to assist these springs in their retraction. The contraction leaf springs 62 urge the mandrel sections together, thereby resulting in a smaller diameter of dispenser 10, when cam lugs 14 are positioned so as not to urge the extension leaf springs 60 outwardly and apart, such as shown in FIG. 1B.

The extension leaf springs 60 and the contraction leaf springs 62 may be molded separately or may be integral to each other, particularly if made of plastic. Alternatively, the leaf springs can also be made of spring steel strip or wire and can be assembled or insert molded.

FIG. 5 illustrates an embodiment with leaf springs 64 between the central shaft 12 and the mandrel sections 44, 46, 48, 50.

A further embodiment is illustrated in FIGS. 6, 7 and 8 wherein the camming action to increase or reduce the diameter of the dispenser 10 is performed by ring-shaped bushings 68, 70, 72, 74. Bushing 68 is positioned inwardly adjacent from second cup 29 and has inclined camming wall 69 abutting an outer end of mandrel 40. Bushings 70, 72 are positioned adjacent to each other in a central location of shaft 12 with respective inclined camming walls 71, 73 abutting the respective inner ends of collet-configured mandrels 40 and 40′ while bushing 74 is positioned inwardly adjacent from first cup 38 with inclined camming wall 75 abutting the outer end of collet-configured mandrel 40′. Additionally, bushing 72 is hollow in order to ride over bushing 70 when the length of dispenser 10 is reduced in order to increase the diameter of dispenser 10. Bushings 70, 72 include coil springs (not shown) therewithin. The collet-configured mandrels 40, 40′ include longitudinally oriented fingers. In the relaxed position at the greatest length of the shaft, the collet-configured mandrels 40, 40′ are in the contracted position so that the dispenser 10 can fit loosely within a coreless roll 100. First cup 38 is joined to bushing 74 and moves in concert therewith and therefore can move toward or away from central shaft 12. Second cup 29 is joined to central shaft 12 and moves in concert therewith. When the cups 29, 38 are urged together, the tapered chamfers on the inclined camming walls 69, 71, 73, 75 press on the internal diameter of the collet-configured mandrels 40, 40′, which radially ramps open the longitudinally-oriented fingers of the collet-configured mandrels 40, 40′. This configuration allows for a greater radial deflection and a lower stress on the finger and further allows for a plastic configuration. The coil springs can be plastic or steel, or possibly other equivalent materials as would be known by one skilled in the art after review of this disclosure.

Further, in the embodiment of FIGS. 6, 7 and 8, the central shaft 12 can be a hollow round cross section, which allows it to be made from a light-weight low-cost extrusion.

FIG. 9 illustrates the dispenser 10 inserted into a roll of film 100, with first cup 38 being inserted thereon.

FIG. 10 illustrates an embodiment wherein first cup 38 is replaced by a handle-shaped attachment 41 which extends perpendicularly from dispenser 10. FIG. 11 illustrates the embodiment of FIG. 10, with roll of film 100 inserted thereon, illustrating that handle-shaped attachment 41 extends beyond the edge of the roll 100.

FIGS. 12, 13, and 14 illustrates first cup 38 which, notwithstanding the orientation illustrated in FIG. 1, is sometimes referred to as a “top cup” as it is intended for removal each time a new film roll 100 is provided. The first cup 38 is illustrated with a slip ring 90 in FIGS. 12 and 13. Slip ring 90 is illustrated in more detail in FIGS. 15 and 16. First cup 38 is configured to allow a human hand to grip the first cup 38 and to provide clearance for the fingers. The surface of the cup 38 at its largest outer diameter 80 is typically round and smooth but could also include flats or ribs 81 that would improve the braking when contacted by the outer sleeve or slip ring 90. At the lower portion of first cup 38 (in the orientation of FIG. 12), stem 36 is provided for snap-fitting into longitudinal blind aperture (or collar) 34 of central shaft 12 as illustrated in FIG. 1. Stem 36 includes molded detents 82 for engaging the longitudinal blind aperture (or collar) 34. The bore of stem 36 further includes push-button pin 84, which includes enlarged distal end 86 which has a greater diameter than the central portion 88. Push-button pin 84 further includes an internal return spring (not shown). The return springs can be molded into the stem 36 or provided as a separate compression spring. When the push-button pin 84 is in its nominal position, enlarged distal end 86 urges molded detents 82 to the outward engaged position. However, when push-button pin 84 is depressed, the enlarged distal end 86 moves away from the detents 82 and the reduced diameter of central portion 88 allows the detents 82 to retract to release the first cup 38 from the central shaft 12.

The cross section of stem 36 can be round and allowed to rotate while detents 82 are engaged by an undercut in the longitudinal blind aperture (or collar) 34. Alternatively, the cross section of stem 36 can be rectangular and not allowed to rotate while detent 82 are engaged by the longitudinal blind aperture (or collar) 34.

The slip-ring sleeves 90 of FIGS. 15 and 16 are provided to prevent heat and abrasion from acting directly on the skin of the operator as the operator holds the ends of the dispenser 10. The slip-ring sleeve 90 is molded similar to the shape of the first cup 38 and snaps over the end cup with a clearance fit therebetween as illustrated in FIGS. 13 and 14. This allows for relative motion between the sleeve 90 and first cup 38 but no motion relative to the hand of the operator when the sleeve 90 is gripped by the operator. The sleeve 90 therefore protects the operator's hand. The circumferential sleeve design also allows the operator to apply a brake torque on the rotating mandrel by using the thumb and fingers to pinch or squeeze the sleeve 90 against the first cup 38. Longitudinally oriented slots 92 improve the ability to squeeze to sleeve. Further, braking ability is increased by the flats or ribs 81 of first cup 38 (see FIG. 13) as well as the flats 94 along the circumference of slip-ring 90 illustrated on FIG. 16.

FIG. 17 is similar to FIG. 1, except that axially oriented handle 39 replaces first cup 38. The axially oriented handle 39 can eliminate the need to remove a fitment each time a new roll is replaced. This makes it easier for the operator to change the roll and minimizes the chance that the operator would lose the fitment. The axially oriented handle 39 could be a separate fitment that snap fits into the central shaft 12 or could be a length extension to the end of central shaft 12. As shown in FIGS. 18 and 19, handle 39 may have stem 36, detents 82 and the related structure previously discussed with respect the first cup 38 shown in FIGS. 12-14. As further shown in FIGS. 18 and 19, sleeve 98, which includes contraction slots 99 molded therein, is placed over the end of central shaft 12, and can act as a rotary brake or clutch when the operator squeezes axially oriented handle 39. This brake torque transits as a tension on the film during dispensing.

In order to use dispenser 10, the user typically starts with the mandrels 40, 42 in a retracted position so as to give the dispenser 10 a smaller diameter. Dispenser 10 is typically then inserted into roll of film 100 (typically coreless) and positioned. First cup 38 is typically then attached. The user then typically causes a longitudinal force against one of the cups 29, 38 thereby urging the cam lugs 14 against the extension leaf springs 60, thereby causing the upper and lower prongs 61, 63 of leaf springs 60 to separate and deflect outwardly and moving the mandrels 40, 42 to an outward position thereby increasing the radius of the dispenser 10 and engaging the roll 100. The film is then dispensed. Of course, different embodiments and different applications may entail a somewhat different series of steps.

Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims. 

1. A dispenser for roll material, comprising: an axial shaft; at least one mandrel in sliding relationship with the axial shaft, wherein the mandrel includes at least a first mandrel section and a second mandrel section which can move toward or away from each other; and wherein relative movement between the axial shaft and the at least one mandrel causes the first mandrel section and the second mandrel section to move away from each other thereby increasing a radius of the dispenser.
 2. The dispenser of claim 1 wherein the at least one mandrel is positioned along an exterior of the axial shaft.
 3. The dispenser of claim 2 wherein the axial shaft includes cam elements.
 4. The dispenser of claim 3 wherein the first mandrel section and the second mandrel section are connected by a spring configuration.
 5. The dispenser of claim 4 wherein the spring configuration includes first springs configured in tension to urge the first mandrel section toward the second mandrel section.
 6. The dispenser of claim 5 wherein the spring configuration includes second springs which can be urged by the cam elements of the axial shaft into an extended position thereby urging the first mandrel section away from the second mandrel section.
 7. The dispenser of claim 6 wherein the first and second mandrel sections move in a radial direction with respect to the axial shaft.
 8. The dispenser of claim 7 wherein the dispenser has a first end and a second end, wherein the first end includes a first configuration for attaching a first fixture and the second end includes an integral second fixture.
 9. The dispenser of claim 8 wherein the second end of the dispenser moves axially in concert with the first mandrel section and the second mandrel section.
 10. The dispenser of claim 9 wherein the first end of the dispenser moves axially in concert with the axial shaft.
 11. The dispenser of claim 10 wherein the first configuration for attaching a first fixture comprises an axially oriented blind aperture.
 12. The dispenser of claim 11 wherein the first fixture includes a stem for insertion into the blind axial aperture.
 13. The dispenser of claim 12 wherein the second fixture includes an axial aperture for allowing axial movement of the axial shaft therethrough.
 14. The dispenser of claim 13 wherein the stem of the first fixture includes detent elements for engaging the blind axial aperture.
 15. The dispenser of claim 14 wherein the first and second fixtures further include respective first and second slip rings over the exterior of the respective first and second fixtures.
 16. The dispenser of claim 15 wherein the first fixture is a handle.
 17. A dispenser for roll material, comprising: an axial shaft including a first appliance on a first end thereof; at least one radially expandable mandrel assembly concentrically outward of the axial shaft; a first bushing with a first inclined camming wall abutting a first end of the at least one radially expandable mandrel; a second bushing with a second inclined camming wall abutting a second end of the at least one radially expandable mandrel; a second appliance on the second bushing; whereby when the first appliance is pushed toward the second appliance, the first and second inclined camming walls are urged against the at least one radially expandable mandrel assembly thereby radially expanding the at least one radially expandable mandrel assembly.
 18. The dispenser of claim 17 wherein the at least one radially expandable mandrel includes first and second radially expandable mandrels, wherein the first bushing abuts a first end of the first radially expandable mandrel and the second bushing abuts a second end of the first radially expandable mandrel, further including a third bushing abutting a first end of the second radially expandable mandrel and a fourth bushing abutting a second end of the second radially expanding mandrel.
 19. The dispenser of claim 18 wherein the radially expandable mandrels include longitudinally extending fingers which are pushed apart by the inclined camming walls.
 20. The dispenser of claim 19 wherein the second bushing abuts the third bushing. 